US2009/0050044 A1 shows a bridle block for a seismic deflector. The three forward and the three aft bridle-lines run into each end of a pitch chain that runs over a motorized cogged wheel which is arranged to relocate the point of attack of towing line on the pitch chain. Thus, the angle of attack of the seismic deflector may be adjusted inwardly or outwardly. A disadvantage of this U.S. application is that it does not necessarily run back to any default position if the motor for the cogged wheel should fail. It also has the weakness that it requires energy supply from the vessel through the towing line or from the deflector via a bridle line. Power supply through cables that are mainly towed mainly across the course line may be vulnerable and increases the diameter of the towing line or one of the bridle-lines.
U.S. Pat. No. 7,658,161 Tønnesen, Western Geco: System for depth control of a marine deflector, shows in FIG. 8B a deflector with fore and aft triples of bridle lines to the upper, middle and lower horizontal plate frame. It is stated in the description that each and all lines may be adjusted inwards and outwards so as for the tilt angle relative to the vertical may be adjusted to control both the depth and angle of attack relative to the course line in the horizontal plane may be adjusted. Tønnesen roughly outlines a number of different possible actuators which have little support with regard to mechanical design, and which have different mechanical weaknesses in the illustrated solutions.
U.S. Pat. No. 4,574,723 describes a deflector with a mechanism wherein the two lowest bridle lines may be slacked out in order for the deflector to lie flat on the sea, making it easier to haul in. It may thus vary the angle of tilt relative to vertical line on a rather extreme way.
EP0168959 Texas Instruments, describes an air gun deflector, a so-called “paravane” that has a longitudinally directed pitch rack which forms a joint for the paravane ends in order to control the fore and aft bridle lines simultaneously. It seems, however, unsuitable for retrofitting because the attachment points on the paravane are not directly prepared for the retrofitting, but wherein a retrofitting of various pulleys and connectors on the paravane is required.
GB2266285 British Aerospace ltd. shows a wild idea of an explosive bomb towed behind an airplane, wherein the bomb may be controlled in a manner similar to a paravane. The bomb is provided with three bridle lines (3a, 3b, 3c) that may be controlled by means of bridle line control winches (8). These do not anticipate the novelty of the actual mechanism presented in the present invention.
U.S. Pat. No. 7,658,161 Tønnesen shows a mechanism for depth control of a deflector.